In this work we expand upon the previous efforts to infer schema information from existing XML documents. We find the inference of structure to be sufficiently researched and focus further on integrity constraints. After briefly introducing some of them we turn our attention to ID/IDREF/IDREFS attributes in DTD. Building on the research by Barbosa and Menelzon (2003) we introduce a heuristic approach to the problem of finding an optimal ID set. The approach is evaluated and tuned in a wide range of experiments.

Approved for public release; distribution is unlimited / The Department of Defense (DoD) is both challenged by the quest for interoperability and capable of the bottom-up development of a solution. The predominant method for achieving interoperability is the development of an intermediate representation that provides a common integration language or data model. An example is Young's Object-Oriented Method for Interoperability (OOMI), which produces a Federation Interoperability Object Model (FIOM) for the resolution of heterogeneities in representation and view of a real-world entity. An FIOM generates a standard for interoperability by associating the non-standard, component system data models into an extensible lattice, which captures translations that resolve data modeling differences. To support the bottom-up creation of an FIOM we; (1) describe a self-similar approach to data storage that allows generic data structures to be manageable, extensible and asynchronously populated, and (2) introduce a lattice concept for facilitating efficient and scalable object inheritance relationships. We assert that DoD's acquisition environment necessitates a distributed approach to solving the interoperability challenge. We present the description of a distributed software system to facilitate the collaborative construction of an FIOM within the existing DoD structure and provide an architecture to guide the development of such a distributed collaborative environment. / Lieutenant, United States Navy

The eXtensible Access Control Markup Language (XACML) is allowing enterprises to implement a standard way of access control to their resources. Security administrators no longer need to duplicate their efforts in writing multiple policies for different resources since a XACML policy can be applied to multiple resources. Companies such as IBM, Sun Microsystems, Oracle, and Cisco are already providing integration of XACML in their products. Although the introduction of XACML has provided enterprises with a better approach of commonly realizing access control, there are still inconsistencies that policy administrators need to be aware of. This thesis identifies some of the inconsistencies in XACML today and introduces a new tool that can be used to visualize some of those inconsistencies. This new tool could be used by a policy administrator to visualize possible conflicting data among a set of policies.

by Yan, Men-Hin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 114-119). / Abstracts in English and Chinese. / Abstract --- p.ii / Acknowledgments --- p.iv / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Storing XML in Database Systems --- p.2 / Chapter 1.2 --- Outline of the Thesis --- p.4 / Chapter 2 --- Related Work --- p.5 / Chapter 2.1 --- Overview of XML --- p.5 / Chapter 2.1.1 --- Extensible Markup Language (XML) --- p.5 / Chapter 2.1.2 --- Data Type Definition (DTD) --- p.6 / Chapter 2.1.3 --- "ID, IDREF and IDREFS" --- p.9 / Chapter 2.2 --- Using Special-Purpose Database to Store XML Data --- p.10 / Chapter 2.3 --- Using Relational Databases to Store XML Data --- p.11 / Chapter 2.3.1 --- Extracting Schemas with STORED --- p.11 / Chapter 2.3.2 --- Using Simple Schemes Based on Labeled Graph --- p.12 / Chapter 2.3.3 --- Generating Schemas from DTDs --- p.12 / Chapter 2.3.4 --- Commercial Approaches --- p.13 / Chapter 2.4 --- Discovering Functional Dependencies --- p.14 / Chapter 2.4.1 --- Functional Dependency --- p.14 / Chapter 2.4.2 --- Finding Functional Dependencies --- p.14 / Chapter 2.4.3 --- TANE and Partition Refinement --- p.15 / Chapter 2.5 --- Multivalued Dependencies --- p.17 / Chapter 2.5.1 --- Example of Multivalued Dependency --- p.18 / Chapter 3 --- Using RDBMS to Store XML Data --- p.20 / Chapter 3.1 --- Global Schema Extraction Algorithm --- p.22 / Chapter 3.1.1 --- Step 1: Simplify DTD --- p.22 / Chapter 3.1.2 --- Step 2: Construct Schema Prototype Trees --- p.24 / Chapter 3.1.3 --- Step 3: Generate Relational Schema Prototype --- p.29 / Chapter 3.1.4 --- Step 4: Discover Functional Dependencies and Candidate Keys --- p.31 / Chapter 3.1.5 --- Step 5: Normalize the Relational Schema Prototypes --- p.32 / Chapter 3.1.6 --- Discussion --- p.32 / Chapter 3.2 --- DTD-splitting Schema Extraction Algorithm --- p.34 / Chapter 3.2.1 --- Step 1: Simplify DTD --- p.35 / Chapter 3.2.2 --- Step 2: Construct Schema Prototype Trees --- p.36 / Chapter 3.2.3 --- Step 3: Generate Relational Schema Prototype --- p.45 / Chapter 3.2.4 --- Step 4: Discover Functional Dependencies and Candidate Keys --- p.46 / Chapter 3.2.5 --- Step 5: Normalize the Relational Schema Prototypes --- p.47 / Chapter 3.2.6 --- Discussion --- p.49 / Chapter 3.3 --- Experimental Results --- p.50 / Chapter 3.3.1 --- Real Life XML Data: SIGMOD Record XML --- p.50 / Chapter 3.3.2 --- Synthetic XML Data --- p.58 / Chapter 3.3.3 --- Discussion --- p.68 / Chapter 4 --- Finding Multivalued Dependencies --- p.75 / Chapter 4.1 --- Validation of Multivalued Dependencies --- p.77 / Chapter 4.2 --- Search Strategy and Pruning --- p.80 / Chapter 4.2.1 --- Search Strategy for Left-hand Sides Candidates --- p.81 / Chapter 4.2.2 --- Search Strategy for Right-hand Sides Candidates --- p.82 / Chapter 4.2.3 --- Other Pruning --- p.85 / Chapter 4.3 --- Computing with Partitions --- p.87 / Chapter 4.3.1 --- Computing Partitions --- p.88 / Chapter 4.4 --- Algorithm --- p.89 / Chapter 4.4.1 --- Generating Next Level Candidates --- p.92 / Chapter 4.4.2 --- Computing Partitions --- p.93 / Chapter 4.5 --- Experimental Results --- p.94 / Chapter 4.5.1 --- Results of the Algorithm --- p.95 / Chapter 4.5.2 --- Evaluation on the Results --- p.96 / Chapter 4.5.3 --- Scalability of the Algorithm --- p.98 / Chapter 4.5.4 --- Using Multivalued Dependencies in Schema Extraction Al- gorithms --- p.101 / Chapter 5 --- Conclusion --- p.108 / Chapter 5.1 --- Discussion --- p.108 / Chapter 5.2 --- Future Work --- p.110 / Chapter 5.2.1 --- Translate Semistructured Queries to SQL --- p.110 / Chapter 5.2.2 --- Improve the Multivalued Dependency Discovery Algorithm --- p.112 / Chapter 5.2.3 --- Incremental Update of Resulting Schema --- p.113 / Bibliography --- p.113 / Appendix --- p.120 / Chapter A --- Simple Proof for Minimality in Multivalued Dependencies --- p.120 / Chapter B --- Third and Fourth Normal Form Decompositions --- p.122 / Chapter B.1 --- 3NF Decomposition Algorithm --- p.123 / Chapter B.2 --- 4NF Decomposition Algorithm --- p.124

" Because of the high volume and unpredictable arrival rates, stream processing systems may not always be able to keep up with the input data streams, resulting in buffer overflow and uncontrolled loss of data. To continuously supply online results, two alternate solutions to tackle this problem of unpredictable failures of such overloaded systems can be identified. One technique, called load shedding, drops some fractions of data from the input stream to reduce the memory and CPU requirements of the workload. However, dropping some portions of the input data means that the accuracy of the output is reduced since some data is lost. To produce eventually complete results, the second technique, called data spilling, pushes some fractions of data to persistent storage temporarily when the processing speed cannot keep up with the arrival rate. The processing of the disk resident data is then postponed until a later time when system resources become available. This dissertation explores these load reduction technologies in the context of XML stream systems. Load shedding in the specific context of XML streams poses several unique opportunities and challenges. Since XML data is hierarchical, subelements, extracted from different positions of the XML tree structure, may vary in their importance. Further, dropping different subelements may vary in their savings of storage and computation. Hence, unlike prior work in the literature that drops data completely or not at all, in this dissertation we introduce the notion of structure-oriented load shedding, meaning selectively some XML subelements are shed from the possibly complex XML objects in the XML stream. First we develop a preference model that enables users to specify the relative importance of preserving different subelements within the XML result structure. This transforms shedding into the problem of rewriting the user query into shed queries that return approximate answers with their utility as measured by the user preference model. Our optimizer finds the appropriate shed queries to maximize the output utility driven by our structure-based preference model under the limitation of available computation resources. The experimental results demonstrate that our proposed XML-specific shedding solution consistently achieves higher utility results compared to the existing relational shedding techniques. Second, we introduces structure-based spilling, a spilling technique customized for XML streams by considering the spilling of partial substructures of possibly complex XML elements. Several new challenges caused by structure-based spilling are addressed. When a path is spilled, multiple other paths may be affected. We categorize varying types of spilling side effects on the query caused by spilling. How to execute the reduced query to produce the correct runtime output is also studied. Three optimization strategies are developed to select the reduced query that maximizes the output quality. We also examine the clean-up stage to guarantee that an entire result set is eventually generated by producing supplementary results to complement the partial results output earlier. The experimental study demonstrates that our proposed solutions consistently achieve higher quality results compared to the state-of-the-art techniques. Third, we design an integrated framework that combines both shedding and spilling policies into one comprehensive methodology. Decisions on the choice of whether to shed or spill data may be affected by the application needs and data arrival patterns. For some input data, it may be worth to flush it to disk if a delayed output of its result will be important, while other data would best directly dropped from the system given that a delayed delivery of these results would no longer be meaningful to the application. Therefore we need sophisticated technologies capable of deploying both shedding and spilling techniques within one integrated strategy with the ability to deliver the most appropriate decision customers need for each specific circumstance. We propose a novel flexible framework for structure-based shed and spill approaches, applicable in any XML stream system. We propose a solution space that represents all the shed and spill candidates. An age-based quality model is proposed for evaluating the output quality for different reduced query and supplementary query pairs. We also propose a family of four optimization strategies, OptF, OptSmart, HiX and Fex. OptF and OptSmart are both guaranteed to identify an optimal solution of reduced and supplementary query pair, with OptSmart exhibiting significantly less overhead than OptF. HiX and Fex use heuristic-based approaches that are much more efficient than OptF and OptSmart. "

Made available in DSpace on 2019-03-30T00:34:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-01-15 / CORBA and COM are often seen as competing technologies. Each one has its own strengths and the main difference between them resides in Operating Systems support. COM is totally oriented toward the Windows platform, while CORBA, since its inception, has been a multiplatform technology. In this study, we prefer not see them as competing technologies. To the contrary, we prefer to find a way to see them as cooperating. One specific draw back in both distributed computing approaches is that, if an application written with them needs to work within the Internet environment, there is a potential problem with firewalls. Most firewalls only allow HTTP traffic, which uses port 80. This means that a distributed system based on COM or CORBA that uses the Internet requires that network administrators leave open a range of numbers, which poses an unwelcome security risk. One solution to this problem is to make remote calls using HTTP protocol. This way, all traffic between the objects passes through port 80 and this eliminates the firewall problems. Another problem is in the necessity to exist symmetry of the used technologies in the modules that compose a distributed system. This work shows ways of gaining cooperation between the two worlds, COM and CORBA, in the Internet environment, through bridges using protocols based in XML and HTTP. Among all possible similar solutions, we choose working with SOAP and XML-RPC for building our own brige. / CORBA e COM são tecnologias freqüentemente vistas como competidoras. Cada uma delas tem seus pontos fortes e a diferença principal entre as mesmas está no suporte que cada uma tem em diferentes Sistemas Operacionais. COM é orientado totalmente à plataforma Windows, enquanto CORBA é uma tecnologia que se propôs, desde a sua especificação inicial, a ser multiplataforma. Neste trabalho, nós não preferimos ver as tecnologias como competidoras. Ao contrário, preferimos encontrar uma forma de vê-las cooperando. Um inconveniente presente em ambas abordagens de computação distribuída é que, se uma aplicação implementada com elas precisar trabalhar usando a Internet há um problema potencial com firewals. A maioria dos firewals autoriza passar apenas o tráfego HTTP, que usa a porta 80. Isso significa que um sistema distribuído baseado em COM ou CORBA e que use a Internet necessita que os administradores de rede deixem uma faixa de números de portas abertas, o que abre brechas de segurança. Uma solução para esse problema é fazer chamadas remotas usando o protocolo HTTP. Com isso, todo o tráfego entre os objetos passa pela porta 80 e elimina-se o problema dos firewals. Outro problema está na necessidade de existir simetria das tecnologias usadas nos módulos que compõem um sistema distribuído. Esta dissertação mostra formas de obter cooperação via Internet entre os dois mundos, COM e CORBA, através de bridges que usam protocolos baseados baseados em XML e HTTP. Dentre as diversas soluções de protocolos deste tipo, escolhemos trabalhar com SOAP e XML-RPC na construção de uma brigde própria.

Made available in DSpace on 2019-04-05T23:09:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-12-12 / This work presents a refactoring approach to aspect oriented code that allows to build refactorings coding only with a declarative language. This approach uses AspectJML, an XML-based representation of AspectJ, to store the syntactic structures of AspectJ code; XSLT, an XML declarative transformation language, to implement the transformations defined by the programming laws required by each refactoring; and an instance of an adaptation of RefaX, an XML-based refactoring framework for Java, to build the AspectJ refactoring tool. The main advantage of this approach is the possibility to build and customize AspectJ refactorings by taking advantage of the high-level pattern-matching and transformation capabilities of XSLT. This approach was evaluated with two refactorings for AspectJ, extract pointcut and extract method calls. / Este trabalho apresenta um processo de refatoração de código orientado a aspectos que permite construir refatorações codificando apenas em uma linguagem declarativa. Esta abordagem utiliza AspectJML, uma representação em XML de AspectJ, para armazenar as estruturas sintáticas do código AspectJ; XSLT, uma linguagem declarativa de transformação para XML, para implementar as transformações definidas pelas leis de programação requeridas para cada refatoração; e uma instância de uma adaptação do RefaX, um arcabouço de refatoração baseado em XML para a linguagem Java, para implementar a ferramenta de refatoração para AspectJ. A principal vantagem desta abordagem é a possibilidade de construir e customizar refatorações de código AspectJ se beneficiando dos recursos de alto nível de casamento de padrões e de transformação oferecidos por XSLT. Esta abordagem foi avaliada com a construção de duas refatorações para AspectJ, extract pointcut e extract method calls.

Experiments were conducted to show the effectiveness of our approaches. / The security of the XML data draws as much attention as the efficiency problem. In this thesis, we study a promising approach to store the accessibility information, which is based on the Compressed Accessibility Map (CAM). We make two advancements in this direction. (1) Previous work suggests that for each user group and each operation type, a different CAM is built. We observe that the performance and storage requirements can be further improved by combining multiple CAMs into an Integrated CAM (ICAM). We explore this possibility and propose an integration mechanism. (2) If the change in structure of the XML data is not frequent, we suggest an efficient lookup method, which can be applied to CAMS or ICAMs, with a much lower time complexity compared to the previous approach. / We take into consideration ID/IDREF attributes, which are common in XML documents. Most related works model an XML document with ID/IDREF attributes as a graph. We retain a tree model, called extended XML tree, in which the IDREF attribute is regarded as an IDREF node, instead of an IDREF edge to the corresponding node. Based on this model, we propose a B+-tree style index (PIN-tree) integrating the essence of the path index and the inverted list approach. A query evaluation algorithm, PINE, based on the model and the indexing is proposed. PINE handles efficiently queries with/without IDREF requests, and IDREF requests can be stated explicitly or implicitly. We prove that PINE is near optimal for twig queries without IDREF requests under the assumption that the number of distinct tag paths to a label is limited. The assumption is proven to be reasonable by experiments. The complexity of PINE for queries with IDREF requests is also given. / XML is emerging as a widely-used platform-independent data representation language. With increasing interests in XML data, techniques concerning XML evolve rapidly. In this thesis, we study two important issues when querying XML data, efficiency and security, which are essential to an XML searching engine. / Jiang Mingfei. / "January 2006." / Adviser: Ada Wai-Chee Fu. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6509. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 136-143). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

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Tese de mestrado integrado. Engenharia Informática e Computação. Faculdade de Engenharia. Universidade do Porto. 2009